The ion exchange characteristics of Amberlite IRA 743 resin for extracting boron from aqueous fluids, have been investigated in detail. The results show that Amberlite IRA 743 resin, a boron-specific ion exchange resin, can quantitatively extract boron as the B (OH)(4)(-) species from weakly basic solution. Some exchangeable anions such as Cl- and SO42- are present, resulting in an increase in pH value of the loaded solution within the column, and the boron in natural aqueous fluids with low pH is also extracted by Amberlite IRA 743 resin. However, the volume of loaded solution must be restricted. The maximum volume of loaded solution giving quantitative extraction of boron decreases for sample solutions of lower pH value. Warm HCl solution is more effective than room temperature HCl solution for eluting boron. from Amberlite IRA 743 resin. The ion exchange characteristics of Amberlite IRA 743 resin for extracting boron from aqueous fluids, have been investigated in detail. The results show that Amberlite IRA 743 resin, a boron-specific ion exchange resin, can quantitatively extract boron as the B (OH)(4)(-) species from weakly basic solution. Some exchangeable anions such as Cl- and SO42- are present, resulting in an increase in pH value of the loaded solution within the column, and the boron in natural aqueous fluids with low pH is also extracted by Amberlite IRA 743 resin. However, the volume of loaded solution must be restricted. The maximum volume of loaded solution giving quantitative extraction of boron decreases for sample solutions of lower pH value. Warm HCl solution is more effective than room temperature HCl solution for eluting boron. from Amberlite IRA 743 resin.